A surface computer generally employs a specialized graphical user interface (GUI) in which traditional GUI input devices such as a keyboard and mouse are replaced by a single, shared, durable, touch-sensitive display surface. Users interact directly with the display surface and applications displayed thereon using touch-based interactions including simple, natural and intuitive hand or finger gestures. Surface computers are now commercially available and are becoming increasingly popular for interactive groupware applications which operate in a collaborative, co-located multi-user setting.